Knock sensor Options

[terrymason]

I've got another thread going where I'm trying to set the mixture on my dual dells, but this got me thinking about a knock sensor. Does anyone here have one? I see there are some aftermarket ones like these:

http://www.dpmotorsport.com/parts/knocklink/home.htm

http://www.msdignition.com/tool_8.htm


Is there a cheaper alternative?

BTW - I tried the search, and kept getting 1000+ hits.

[newto914s]

I didn't think knock sensors work to well on air cooled cars cause they are so much noisier then water cooled cars. On the SDS sight it illudes to that.

[terrymason]

you know, that could be true. One of my coworkers asked how I could tell if my engine was pinging without a knock sensor.

[Crazyhippy]

A calibrated ear.... and the ability to read the plugs so you know it's in tune.

[ws91420]

knock sensor is only good on a car w/ computer controlled ignition. It is used to retard the timing when detonation occurs (knocking)

[Brando]

964s and 993s had knock-retard sensors, and mechanical lifters. A knock-retard system is only good if you're running a computer-controlled ignition. If you wanted to, you could adapt a late 944 (post 85½) injection and ignition system to the 914. It also has a knock-retard system and is digital (and would probably cost less).

[Crazyhippy]

Just a light would be helpful... Think of it as an idiot light (Hey idiot, there's somethign wrong) Could use it as a tuning tool (advance timing till knock occurs or power falls off under heavy load.

BJH

[terrymason]

I guess something like this is what I'm talking about :

http://forums.nasioc.com/forums/showthread.php?t=768081

Just a light that would flash when a knock is heard, so that I'd know something is wrong. It probably wouldn't be much good on a daily basis, but it could be neat. Any reason that something like this wouldn't work?

[fiid]

Knock is usually used by the engine management computer to retard ignition and to deal with poor quality gas or gas of a lower grade than intended. There's not a whole lot of point if you don't have an engine managment computer.

There is a megasquirt knock circuit available which basically turns a light on - that's what I have in my car although mine is actually hooked up to the megasquirt.

There may be other issues though - Knock sensors are basically microphones, and I don't know that they are thermally resistant enough to sit where they would need to be (probably on the cylinder body for a TIV) - plus mounting would mess with the cooling some.

I'd get a WBO2 first if I were you.... it will give you more actionable information.

[Brando]

I'd be kind of iffy actually putting a knock-sensing unit on a Type 4. Depending on sensativity, of course... These engines have a lot of mechanical noise...

[terrymason]

I'd get a WBO2 first if I were you.... it will give you more actionable information.

What's a WB02?

[Mark Henry]

WB02 = Wide Band O2 sensor

Air cooled engines are too noisy for a knock sensor....it can be made to work but it can also fuch you up when tuning. Not worth messing with.

[fiid]

Since knock sensors are actually microphones, and knock comes at a certain time (in the combustion cycle) and is of predicable pitch (due to the resonant frequencies of the combustion chamber) - I'd guess that it's theoretically possible to overcome the noise issues on a TIV - but in practice - it would take a lot of R&D. It wouldn't be easy (IMG:style_emoticons/default/sad.gif). I think the megasquirt guys are making progress on this kind of stuff though.

A WideBand Oxygen sensor will tell you what your mixture is - i.e. lean or rich - this information can be applied to both carbs and fuel injection (although fuel injection systems can actually read the output in real time and adjust themselves to your engine).